Ship propulsion power plant



Oct. 25, 1966 E. G. HUTCHINGS 3,280,559

SHIP PROPULSION POWER PLANT Filed Sept. 25, 1964 2 Sheets-Sheet l Inventor Edward G. Hurchings Attorney Oct. 25, 1966 Filed Sept.

E. G. HUTCHINGS 3,280,559

SHIP PROPULSION POWER PLANT 2 Sheets-Sheet 2 v?" I m M 7 liiiii h United States Patent 3,280,559 SHIP PROPULSION PDWER PLANT Edward G. Hutchings, London, England, assiguor to Babcock & Wilcox Limited, London, England, a corporation of Great Britain Fiied Sept. 25, 1964, Scr. No. 399,312 Claims priority, application Great Britain, Sept. 26, 1963, 33,030/ 63 13 Claims. (Cl. 60-73) This invention relates to ship propulsion power plant and is particularly concerned with the boilers of such plants.

In order to obtain efiicient operation in steam turbine ship propulsion power plant a high, temperature of superheat with a reheating of the steam between stages is desirable. Reheating, however, tends to lead to complication since both the temperature of superheat and the temperature of reheat must be maintained at safe and acceptable values during normal ahead operation whilst during an astern operation damage to the reheater tubes by overheating must be avoided.

One way of preventing overheating of the reheater tubes is to provide two separately fired furnaces with the reheater associated with one furnace only so that during astern operation the furnace associated with the reheater can be shut down. Using two furnaces has the disadvantage that the two furnaces require more space than is 'usually available for the steam generating portion of the ship propulsion power plant and are more complicated to control.

By the present invention there is provided in a ship propulsion power plant a tubulous vapour generator adapted to supply superheated vapour to an engine and to reheat the vapour between engine stages, which vapour generator includes a furnace chamber, superheater tubes and reheater tubes arranged to be heated by combustion gases from the furnace chamber, and means whereby overheating of the reheater tubes may be prevented when there is insuflicient or no steam circulating in the reheater tubes for this purpose, whilst allowing the desired quantity of superheated steam at the required temperature to be maintained.

Further, by the present invention there is provided in a ship propulsion power plant a tubulous vapour generator adapted to supply superheated vapour to .an engine and to reheat the vapour between engine stages, which, vapour .generator includes a furnace chamber, a first gas pass and a second gas pass in parallel therewith, both of said gas passes containing heat exchange tubes. The reheater includes heat exchange tubes in the second pass, and the superheater includes heat exchange tubes disposed in the path of the combustion gases which pass through at least one of the passes. Means are provided whereby overheating of the reheater tubes may be prevented when there is insufficient or no steam circulating in the reheater tubes, whilst allowing the desired quantity of superheated steam at the required temperature to be maintained which means includes heat exchange tubes disposed in the path of the gases between the furnace chamber and the reheater tubes and damper means whereby the flow of gas through the passes can be regulated.

By providing heat exchange tubes in the second pass the gases from the furnace are cooled before they reach the reheater tubes, and the damper means can be used to redistribute the flow of the gases from the furnace through the first and second passes when there is insufiicient or no steam circulating in the reheater tubes to prevent overheating of the reheater tubes whilst allowing the desired quantity of superheated steam at the required temperature to be maintained.

The heat exchange tubes in the first and second passes may be vapour generating tubes, or vapour heating tubes such .as, economiser and boiler tubes or superheater tubes and preferably include a primary superheater in the second pass and .a secondary superheater in the first pass. The heat exchange tubes disposed in the path of the gases between the furnace chamber and the reheater tubes preferably include the primary superheater when a primary and a secondary superheater are included in the tubulous vapour generator.

In the accompanying drawings which illustrate an embodiment of the present invention:

FIGURE 1 is a diagrammatic sectional side view along II of FIGURE 2 of a tubulous vapour generator for use in a ship propulsion power plant;

FIGURE 2 is a diagrammatic sectional end view along IIII of FIGURE 1.

Referring to FIGURES 1 and 2 there is shown a boiler setting 1 front and rear walls 2 and 3 and side walls 4 and 5. The boiler setting 1 is enclosed in outer insulation 6 and a casing 7 (only a part of which is shown). The setting 1 is divided by a transverse tube wall 8 to form a furnace chamber 9 at the front of the setting 1 and a gas up-flow passage 10 at the rear. The gas up-flow passage 10 is divided by a tubular membrane wall 11 to form a first gas pass 12 and a second gas pass 13.

The tube walls 2, 4 and 5 are spaced from the casing to form combustion air paths and oil burners 14 are mounted in the roof of the furnace chamber 9. The tube walls 2 and 3 and the transverse tube wall 8 are connected at their lower ends to a header 15. Tube wall 2 and transverse tube wall 8 are connected at their upper ends to a header 16. The tube wall 3 is connected at its upper end to a header 17. The tube walls 4, 5 and 11 are connected at their lower ends to headers 18, 19 and 20 respectively, and at their upper ends to headers 21, 22 and 23 respectively. The transverse tube wall 8 has the lower ends of its tubes staggered at 24 to provide -a gas outlet from the furnace chamber 9 to the first gas pass 12 and the second gas pass 13. The header 21 is connected by pipes 25, 26 and 27 to a separator drum 28. The separator drum 2-8 is connected by pipes 29, 30 and 31 to header 18. The headers 22 and 19 are connected in a similar manner to the separator drum 28 as headers 21 and 18. The header 23 is connected at its ends to the headers 16 and 17 and the header 20 is connected by pipes to the separator drum 28 in a similar manner to pipes 29, 30 and 31. The header 16 is connected by two pipes, one of which is indicated at 32, to the separator drum and header 17 is connected to the separator drum 28 in a similar manner. The separator drum 23 is connected by two pipes, one of which is indicated at 33, to the header 15.

In the second gas pass 13 there are the sinuous nested tubes of a primary superheater 34 connected at the lower ends to a header 65 (FIGURE 1) and at the upper ends to a header 36. The header 35 has an inlet (not shown) connected to receive vapour from the separator drum 28. The header 36 has an outlet (not shown) connected to a header 37 (FIGURE 1) which is in turn connected to the inlets of a secondary superheater 38 composed of two banks of sinuous nested tubes. The Outlets from the secondary superheater 33 are connected to a header 39 which is connected to the first stages of a marine turbine engine (not shown).

Above the primary superheater 34 in the second gas pass 13 are reheater tubes 49 which supply a header 41 and have their inlets connected to further reheater tubes 42. The further reheater tubes 42 have their inlets connected to a header 43. The headers 41 and 43 are connected between stages of the marine turbine engine header 46 passes the feed water to the separator drum 28.

The casing 7 contains the reheater tubes 42 which are above the first gas pass 12 and the second gas pass 13 and provide a gas outlet 47. Plates 48 and 49 form the side walls of the casing 7 and a baflie plate 50 separates the gas outlets from the first gas pass 12 and the second gas pass 13. Control dampers 53 separated by baffles 54 are arranged below the gas outlet 47 and above the first gas pass 12 and control dampers 51 separated by baflies 52 arranged below the gas outlet 47 above the second gas pass 13. Soot blowers 55 and 56 are provided for cleaning the tubes. The soot blowers 56 are normally situate-d outside the boiler, whilst the boiler is generating steam and are moved'into the boiler when required to remove soot from the tubes.

In operation during a normal ahead operation feed water from the ships feed water system is pasesd via the economiser tubes 44 in the first gas pass 12 to the separator drum 28. The oil burners 14 are fired with the dampers 51 and 53 open so that the hot combustion gases from the oil burners 14 pass downwardly through the furnace chamber 9 between the staggered tubes 24 of the transverse tube wall 8 and then upwardly through the first gas pass 12 and the second gas pass 13 in separate streams. The relative flows through the passes 12 'and 13 being dependent upon the adjustments of the dampers 51 and 53. The combustion air is drawn along the spaces between the tube walls 2, 4 and and the casing 7.

Water from the header 15 passes along the tubes in,-

36 and 37, through the secondary superheater 38 to the header 39 from which superheated steam is fed to the I first stages of the marine turbine engine. Hot water from the separator drum 28 is passed back to the headers 16, 18 and 19 and 20. When the superheated steam has passed through the first stages of the marine turbine it is fed to the header 43, through the tubes in the reheaters '42 and 40 to the header 41 which feeds the steam to the later stages of the marine turbine. After the steam has passed through the later stages of the marine turbine it is condensed and returned to the separator drum 28 via the ships feed water system and the economiser 44.

When it is required to perform a normal astern op-' eration, no flow of vapour is required through the reheater and so the dampers 51 and 53 are adjusted to direct the flow of most of the combustion gases through the first gas pass 12 and the flow of vapour through the reheaters 40 and 42 is discontinued. Steam which has passed through the primary superheater 34 and the secondary superheater 38 is now. passed to a different sets of turbine blades which are arranged to be driven in the opposite direction and from which the steam is condensed and returned to the separator drum 28 via the feed system of the tubes 44. The primary superheater 34 reduces the temperature of the combustion gases before they reach the reheaters 40 and .42 whilst the circulation of vapour through the reheater 40 is discontinued.

The combustion gases flowing from the first gas pass 12 over the reheater 42 will have been cooled by the secondary superheater 38 and the economiser 44.

If desired all of the reheater may be placed inside the 4' second gas pass 13 beneath air heating tubes and further economiser tubes may be placed above the dampers 51 and 53.

All of the superheater tubesof the primary superheater 34 and the secondary superheater 38 may be placed in either the first or the second gas pass 12 and other vapour heating tubes, for example, economiser tubes may be placed beneath the reheater 40 in the second gas pass 13. In an alternative arrangement the tubes beneath the reheater 42 may :be in banks which perform different func-. tions, for example, they may be in banks which are used for vapour generating and/or superheating and vapour generating tubes may be substituted for all or part of the economiser tubes in either pass. The gas outlet 47 may contain economiser and/or air heating tubes.

One or more additional gas passes may be provided in parallel with the firt and second gas pases 12 and 13, the additional gas pass or passes may contain heating tubes, such as, for example, superheater tubes, economiser tubes or =vapour generating tubes. The additional gas pass or passes may be provided with dampers.

In a further embodiment all or part of the superheater tubes may be disposed in a gas path for the furnace gases between the furnace chamberand at lea-st one of the passes, and vapour generating tubes may be arranged upstream of these superheater tubes. heater tubes may be disposed in a horizontal gaspassage between the furnace chamber and the gas inlets to the first and second passes. The outlet end of the horizontal gas passage may be divided to form entrances to the gas passes and vapour generating tubes may be disposed in the entrances extending between an upper drum and a lower drum, both of which form a part of the walls of the entrances.

' An attemperator may be used to cool the steam between the primary superheater 34 and secondary superheater 38 or at the outlet of the secondary superheater 38.

The reheater tubes 40 may be placed in a portion of the second gas pass 13 which is downstream of the dampers 51 and bafiles 52.

Preferably the cross-sectional areas of the gas passes and/or the areas of the heat exchange surfaces provided by the primary and secondary superhea'ting tubes are so arranged that changes in the temperature of the superheated steam leaving the secondary superheater 38, caused by actuating the dampers 51 and 53 are'minirnised. The

second gas pass 13 only may be fitted with dampers by omitting, the dampers 53. Any additional gas passes may still be fitted with dampers even though the dampers 53 are omitted.

In an alternative embodiment the first and second gas passes may be situated at different sides of the furnace chamber and the separator drum 28 may be situated between the gas passes.

The separator drum 28 is preferably provided with turbine means including a vapor generator, said vapor generator including walls defining a furnace chamber,

means for burning fuel in said furnace chamber to produce high temperature heating gases, means defining a heating gas pass connected for the flow therethrough of high temperature gases from said furnace chamber, superheater and reheater tube banks disposed in said heating gas pass, and means for preventing overheating of the tubes of said reheater tube bank when superheated steam is supplied to said astern drive turbine means.

the dampers 51. Combustion All of the super- 2. A ship propulsion system comprising forward drive turbine means including a superheat stage and a reheat stage, astern drive turbine means including only a superheat stage, and means for selectively supplying superheated and reheated vapor to said forward drive turbine means or only superheated vapor to said astern drive turbine means including a vapor generator, said vapor generator including walls defining a furnace chamber, means for burning fuel in said furnace chamber to produce high temperature heating gases, means defining first and second parallel fiow heating gas passes connected for the flow the-rethrough of high temperature heating gases from said furnace chamber, a superheater tube bank positioned in said first heating gas pass, a reheater tube bank positioned in said second heating gas pass, and means including dampers for reducing the fiow of said heating gases through said second heating gas pass to prevent overheating of the tubes of said reheater tube bank when superheated vapor is supplied to said astern drive turbine means.

3, A ship propulsion system comprising forward drive turbine means including a superheat stage and a reheat stage, astern drive turbine means including only a superheat stage, and means for selectively supplying superheated and reheated vapor to said forward drive turbine means or only superheated vapor to said astern drive turbine means including a vapor generator, said vapor generator including walls defining a furnace chamber, means for burning fuel in said furnace chamber to produce high temperature heating gases, means defining first and second parallel flow heating gas passes connected for the flow therethrough of high temperature heating gases from said furnace chamber, a reheater tube bank positioned in said second heating gas pass, a first superheater tube bank positioned upstream gas fiow-wise of said reheater tube bank, a second superheater tube bank positioned in said first heating gas pass, and means including dampers for reducing the flow of said heating gases through said second heating gas pass to prevent overheating of the tubes of said reheater tube bank when superheated vapor is supplied to said astern drive turbine means.

4. A ship propulsion unit according to claim 3 wherein said first and second superheater tube banks comprise respectively at least portions of a primary and secondary superheater.

5. A ship propulsion system comprising forward drive turbine means including a superheat stage and a reheat stage, astern drive turbine means including only a superheat stage, and means for selectively supplying superheated and reheated vapor to said forward drive turbine means or only superheated vapor to said astern drive turbine means including a vapor generator, said vapor generator including walls defining a furnace chamber, means for burning fuel in said furnace chamber to produce high temperature heating gases, means defining first and second parallel flow heating gas passes connected for the fiow therethrough of high temperature heating gases from said furnace chamber, a superheater tube bank positioned in said first heating gas pass, a plurality of fiuid heating tube banks including a reheater tube bank positioned in said second heating gas pass, said reheater tube bank being arranged downstream gas flow-wise of the remaining fluid heating tube banks in said second heating gas pass, and means including dampers for reducing the flow of said heating gases through said second heating gas pass to prevent overheating of the tubes of said reheater tube bank when superheated vapor is supplied to said astern drive turbine means.

6. A ship propulsion system comprising forward drive turbine means including a superheat stage and a reheat stage, astern drive turbine means including only a superheat stage, and means for selectively supplying superheated and reheated vapor to said forward drive turbine means or only superheated vapor to said astern drive turbine means including a vapor generator, said vapor generator comprising walls including vapor generating tubes defining a furnace chamber having a heating gas outlet, means for burning fuel in said furnace chamber to produce high temperature heating gases, wall means including vapor generating tubes defining an upright convection gas pass connected at one end thereof to receive high temperature heating gases from said furnace chamber, fluid cooled partition means dividing said convection gas pass into first and second parallel flow heating gas passes, a secondary superheater tube bank positioned in said first heating gas pass, a primary superheater tube bank and a reheater tube bank positioned in said second gas pass for the respective serial fiow of heating gases thereover, and means including dampers for reducing the flow of said heating gases through said second heating gas pass to prevent overheating of the tubes of said reheater tube bank when superheated vapor is supplied to said astern drive turbine means.

7. A ship propulsion system comprising forward drive turbine means including a superheat stage and a reheat stage, astern drive turbine means including only a superheat stage, and means for selectively supplying superheated and reheated vapor to said forward drive turbine means or only superheated vapor to said astern drive turbine means including a vapor generator, said vapor generator comprising walls including vapor generating tubes defining an upright furnace chamber having a heating gas outlet at the lower end thereof, burner means arranged to burn fuel in the upper end of said furnace chamber to produce high temperature heating gases, wall means including vapor generating tubes defining an upright convection gas pass laterally adjacent said furnace chamber and connected at its lower end to receive high temperature heating gases from said furnace chamber, upright fluidcooled partition means dividing said convection gas pass along a portion of its height into first and second parallel flow heating gas passes, a secondary superheater tube bank positioned in said first heating gas pass, a primary superheater tube bank positioned in said second heating gas pass, a first reheater tube bank positioned in said second heating gas pass above said primary superheater tube bank, a second reheater tube bank positioned in said convection pass above said partition means, said first and second reheater tube banks being connected for the serial flow of vapor therethrough, and means including dampers disposed at least in said second heating gas pass above said first reheater tube bank for reducing the flow of said heating gases through said second heating gas pass to prevent overheating of the tubes of said first reheater tube bank when superheated vapor is supplied to said astern drive turbine means.

8. A ship propulsion system comprising forward drive turbine means including a superheat stage and a reheat stage, astern drive turbine means including only a superheat stage, and means for selectively supplying superheated and reheated vapor to said forward drive turbine means or only superheated vapor to said astern drive turbine means including a vapor generator, said vapor generator including upright walls defining a boiler setting, a transversely disposed wall dividing said setting into a furnace chamber and a convection gas flow passage, said furnace chamber and said passage communicating at their lower ends, burner means arranged at the upper end of said furnace chamber for firing downwardly thereinto to thereby effect the flow of heating gases downwardly through said furnace and upwardly through said gas flow passage, superheater and reheater tube banks disposed in said gas flow passage, and means for preventing overheating of the tubes of said reheater tube bank when superheated steam is supplied to said astern drive turbine means.

9. The system according to claim 8 wherein said vapor generator further includes a wall dividing said convection gas flow passages into a pair of parallel-flow gas passes, and said superheater and reheater tube banks are disposed in one of said gas passes.

7 10. The system according to claim 9 wherein said means for preventing overheating includes a damper means disposed above said one of said gas passes for bypassing at least a substantial portion of heating gases around said reheater tube bank.

11. The system according to .claim 10 wherein an economizer tube bank is disposed in the other of said heating gas passes.

12. The system according to claim 11 wherein additional damper means are disposed at the upper end of said other of said heating gas passes, said damper and said 8 additional damper means cooperating to provide superheater and reheater temperature control.

13. The system according to claim 12 wherein an additional economizer tubebank is disposed above said damper means in said convection gas flow passage.

No references cited.

MARTIN P. SCHWADRON, Primary Examiner.

10 R. R. BUNEVICH, Assistant Examiner. 

1. A SHIP PROPULSION SYSTEM COMPRISING FORWARD DRIVE TURBINE MEANS INCLUDING A SUPERHEAT STAGE AND A REHEAT STAGE, ASTERN DRIVE TURBINE MEANS INCLUDING ONLY A SUPERHEAT STAGE, AND MEANS FOR SELECTIVELY SUPPLYING SUPERHEATED AND REHEATED VAPOR TO SAID FORWARD DRIVE TURBINE MEANS OR ONLY SUPERHEATED VAPOR TO SAID ASTERN DRIVE TURBINE MEANS INCLUDING A VAPOR GENERATOR, SAID VAPOR GENERATOR INCLUDING WALLS DEFINING A FURNACE CHAMBER, MEANS FOR BURNING FUEL IN SAID FURNANCE CHAMBER TO PRODUCE HIGH TEMPERATURE HEATING GASES, MEANS DEFINING A HEATING GAS PASS CONNECTED FOR THE FLOW THERETHROUGH OF HIGH TEMPERATURE GASES FROM SAID FURNANCE CHAMBER, SUPERHEATED AND REHEATER TUBE BANKS DISPOSED IN SAID HEATING GAS PASS, AND MEANS FOR PREVENTING OVERHEATING OF THE TUBES OF SAID REHEATER TUBE BANK WHEN SUPERHEATEDF STEAM IS SUPPLIED TO SAID ASTERN DRIVE TURBINE MEANS. 